Apparatus for sampling the human breath



n 1957 G. K. E. H. STAMPE 2,795,223

APPARATUS FOR SAMPLING THE HUMAN BREATH Filed Aug. 21, 1953 K 5 Z m 5 s 1 z I. E

United States Patent APPARATUS FOR SAMPLING THE HUMAN BREATH Gerhard Karl Emil Heinrich Stampe, Lubeck, Germany, assignor to Otto Heinrich Drager, Lubeck, Germany Application August 21, 1953, Serial No. 375,710

Claims. (Cl. 128-2) This invention relates to the obtaining of samples of air from the lungs. In particular, the invention is directed to an apparatus for obtaining a sample of the alveolar air from the lungs.

When a sample of the human breath is taken, it is important that the sample actually consist of the air coming from the alveoles, and not the air which exists in the mouth, throat, and the bronchials, as this air does not undergo the changes in composition such as occurs in the alveolar air in the lungs. In some people it is particularly difiicult to obtain an air sample which consists exclusively of the alveolar air. While it is possible for a person to first exhale a part of the air in the lungs, and then exhale the remaining air for the purpose of taking a sample, this in no way assures that the sample received in the sampling apparatus does not contain a substantial amount of air from the mouth, throat and bronchials.

The object of the instant invention is to produce an apparatus in which it is assured that the air from the mouth, throat and bronchials is first exhausted, and then a sample of the alveolar air is obtained.

In general, this object is obtained by forming a simple apparatus in which the first part of the air exhaled from the lungs into the apparatus is side-tracked, and then the alveolar air is collected for purposes of sampling. The first air which is side-tracked is collected in a chamber of a size so as to receive the maximum possible amount of air capable of being held in the mouth, throat and bronchials. The alveolar air is then collected in a second chamber. This is done by having a tube having an inlet end adapted to be held in the mouth, a branch which is connected to a gas-tight bag for receiving the air from the mouth, throat and bronchials, and another branch having a second chamber for receiving the alveolar air, this latter branch including means for preventing the passage of air exhaled into the second chamber until the air from the mouth, throat and bronchials has filled the first chamber.

The means by which the objects of the invention are obtained are described more fully with respect to the accompanying drawings, in which:

Figure l is a cross-sectional view through one form of the invention;

Figure 2 is a cross-sectional view through a modified form of the invention; and

Figure 3 is a cross-sectional view through a further modified form of the invention.

As shown in Figure 1 the apparatus is composed of a tube 2 having a mouthpiece 1 This tube has a by-pass duct 3 communicating with a first chamber 4. This chamber 4 preferably is a collapsible bag which has scarcely any elasticity, and has a volume such as to receive only the maximum amount of air which is contained in the mouth, throat and bronchials. A second tube 5 contains a spring-pressed valve 6, and further communicates with a second chamber 7, which again is a collapsible bag of little elasticity. Tube 5 has a telescopic joint 8 with tube Zi A. discharge duct containing cock valve: 9 isjoined to tube 5 between valve 6 and chamber 7.

In use, thepersomfromwhom anair sample is to be taken, cxhales his air through. mouthpiece 1. A first portion of the exhaled air coming from the mouth, throat and bronchials is prevented from entering chamber 7 by reason of .valve 6, and-accordingly, fills chamber 4. After chamber 4 has been filled, the pressure of the continuing exhaled air forces valve 6 open, and the alveolar air then passes into chamber 7, valve 9 of course being closed. The aveolar air in chamber 7 is then drawn off into a gas analyzing apparatus by opening valve 9.

The bags forming chambers 4 and 7 are of moisture resistant, pliable, but barely elastic material, so that under all conditions of pressure which may arise when filled with exhaled air, they contain a certain amount of air when completely filled. Bag 4 has a capacity of approximately 600 00., this being the upper limit of the possible amount of air contained in the mouth, throat and bronchials. The size of alveolar bag 7 depends upon the amount of air to be sampled. When being used, the bags first are completely emptied by pressing them flat, and then filled with the exhaled air.

In Figure 2 the resistance element is composed of a porous indicator cartridge 11 inserted in tube 5 and connected to tube 2 by a sleeve 10. This resistance element impedes the passage of air into bag 7 so that bag 4 will first be filled, and then the alveolar air will be forced through element 11 into bag 7. The element 11 can include commonly known indicators which can measure the amount of air passing through the tube, and the concentration of any desired component therein. For example, the apparatus is particularly adapted for determining the content of carbon dioxide in the exhaled air. Also, the amount of alcohol in the exhaled air can be indicated, as the alcohol content of the exhaled air is dependent upon the alcohol content of the blood.

In Figure 3 the tube 2 is connected to the tube 5 by means of a reduced section 12 in the nature of a capillary. This reduced section offers sufiicient resistance to the passage of air so that the air from the mouth, throat and bronchials will first collect in bag 4, and the alveolar air will then subsequently enter the bag 7.

The bag 4 can be replaced by an evacuated container, which is connected to tube 2 by means of a suitable valve. Thus, when the first air from the mouth, throat and bronchials is exhaled, the aforesaid valve can be opened, and this air drawn into the evacuated chamber along with a small portion of alveolar air. As soon as chamber 4 is filled, the subsequently exhaled alveolar air is forced into chamber 7 as heretofore. described. The possibility of a small portion of the first exhaled air getting into chamber 7 in the constructions of Figures 2 and 3, is substantially eliminated by the spring-pressed valve 6 of Figure 1.

Having now described the means by which the objects of the invention are obtained, I claim:

l. An apparatus for receiving a sample of exhaled alveolar air comprising a tube having a mouthpiece, a first chamber communicating with said tube for receiving and being filled with the first portion of the exhaled air, a second chamber communicating with said tube for subsequently exhaled alveolar air after the first chamber is filled, and a resistance element in said tube intermediate said first and second chambers to prevent air from flowing into said second chamber until after said first chamber is filled.

2. An apparatus as in claim 1, said chambers comprising collapsible gas-tight bags.

3. An apparatus as in claim 1, said resistance element comprising a narrowed capillary section in said tube.

Patented June. 11, 1957 References Cited in the file of this patent UNITED STATES PATENTS Regelsbe'rger Sept. 25, 1928 10 Schroeder June 2, 1931 4 OTHER REFERENCES A Comparison of Methods for Determining the Respiratory Exchange of Man (Carpenter), pub. by Carnegie Institution of Washington (No. 216), 1915, pp. 67-68. A copy of this publication is in Division 55. 

